1. Field of the Invention
The present invention relates generally to a spinning nozzle, and more specifically to a nozzle for applying twists inherent in a bundled spun yarn to a fiber bundle drafted by a pneumatic spinning apparatus.
2. Related Art Statement
In a pneumatic spinning apparatus, a fiber bundle drafted and supplied from front rollers of a drafting device is twisted by a spinning nozzle comprising a first nozzle and a second nozzle arranged in a line along a passage of the fiber bundle. A tubular yarn passage provided with jetting holes for jetting compressed air toward the fiber bundle is formed in the first nozzle. A tubular yarn passage is also formed in the second nozzle and is provided with jetting holes for jetting compressed air into the tubular passage to produce swirling air current swirling in an opposite direction to the swirling air current produced in the first nozzle.
The second nozzle is provided in its outlet end portion with a balloon controller having a through hole of a diameter smaller than the diameter of the tubular yarn passage.
The conventional balloon controller 12 of the second nozzle 2 is cylindrical and the through hole 13 has a circular cross section as shown in FIG. 4.
The balloon controller 12 limits the diameter of the balloon of the false-twisted fiber bundle indicated by alternate long and short dash line Ba in FIG. 4 so that the twists inserted in the fiber bundle in the second nozzle 2 propagate stably to a portion of the fiber bundle in the first nozzle 1. Accordingly, it is desirable that the through hole 13 has the smallest possible diameter. However, if the diameter of the through hole 13 is excessively small relative to the yarn count, the air blown into the tubular yarn passage of the second nozzle cannot be discharged from the second nozzle, which makes the spinning operation impossible.